Brazilian President Luiz Inacio Lula da Silva has ordered the military to Rio de Janeiro state to help curb a wave of gang violence that has killed about 20 people in the past week.

President da Silva issued the order Thursday in response to a request by Rio's governor, Sergio Cabral. It is not clear how many federal troops will be sent to the state.

Mr. da Silva has described the violence in the business and tourist areas of the state capital, Rio de Janeiro, as "terrorism." He said such violence must be dealt with by, in his words, "the strong hand of the Brazilian state."

The deployment comes hours after armed robbers attacked a van carrying Croatian and German tourists from Rio's international airport into the city. Officials say the gunmen stole money, passports and jewelry from the six tourists but that none of the visitors was injured.